• 순수 JPA 리포지토리와 Querydsl
• 동적 쿼리와 성능 최적화 조회 - Builder 사용
• 동적 쿼리와 성능 최적화 조회 - Where절 파라미터 사용
• 조회 API 컨트롤러 개발

✅순수 JPA 리포지토리와 Querydsl

순수 JPA 리포지토리

@Repository
public class MemberJpaRepository {
    private final EntityManager em;
    private final JPAQueryFactory queryFactory;
    public MemberJpaRepository(EntityManager em) {
        this.em = em;
        this.queryFactory = new JPAQueryFactory(em);
    }
    public void save(Member member) {
        em.persist(member);
    }
    public Optional<Member> findById(Long id) {
        Member findMember = em.find(Member.class, id);
        return Optional.ofNullable(findMember);
    }
    public List<Member> findAll() {
        return em.createQuery("select m from Member m", Member.class)
                .getResultList();
    }

    public List<Member> findByUsername(String username) {
        return em.createQuery("select m from Member m where m.username = :username", Member.class)
                .setParameter("username", username)
                .getResultList();
    }
}

순수 JPA 리포지토리 Test

@SpringBootTest
@Transactional
class MemberJpaRepositoryTest {

    @Autowired
    EntityManager em;

    @Autowired MemberJpaRepository memberJpaRepository;

    @Test
    public void basicTest() {
        Member member = new Member("member1", 10);
        memberJpaRepository.save(member);

        Member findMember = memberJpaRepository.findById(member.getId()).get();
        assertThat(findMember).isEqualTo(member);

        List<Member> result1 = memberJpaRepository.findAll();
        assertThat(result1).containsExactly(member);

        List<Member> result2 = memberJpaRepository.findByUsername("member1");
        assertThat(result2).containsExactly(member);
    }
}

Querydsl 사용

순수 JPA 리포지토리 - Querydsl 추가

public List<Member> findAll_Querydsl() {
        return queryFactory
                .selectFrom(member).fetch();
    }

    public List<Member> findByUsername_Querydsl(String username) {
        return queryFactory
                .selectFrom(member)
                .where(member.username.eq(username))
                .fetch();
    }

JPAQueryFactory 스프링 빈 등록

다음과 같이 JPAQueryFactory 를 스프링 빈으로 등록해서 주입받아 사용해도 된다.

package study.querydsl.config;

import com.querydsl.jpa.impl.JPAQueryFactory;
import jakarta.persistence.EntityManager;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class QuerydslConfig {

    @Bean
    JPAQueryFactory jpaQueryFactory(EntityManager em){
        return new JPAQueryFactory(em);
    }
}

✅동적 쿼리와 성능 최적화 조회 - Builder 사용

MemberTeamDto - 조회 최적화용 DTO 추가